The invention relates to an apparatus for spray coating of vessel mouths with at least one spray nozzle.
It is the case with many liquids, that there are difficulties in pouring them, because at the end of the pouring operation a residue of liquid runds down on the outside of the vessel mouth. The soiling of the vessels, for example glass bottles, caused thereby is undesirable and must be prevented, especially with regard to toxic, aggressive or otherwise dangerous liquids. For this purpose, pouring rings forming a sharp breakaway edge which assists the breakaway of the stream of liquid at the end of the pouring operation are conventtionally attached to the vessel mouths. On the other hand, these pouring rings consist of a plastic which usually has a lower surface affinity with the liquid than the glass surface.
The manufacture and attachment of these pouring rings involve a relatively high outlay in terms of production. The pouring rings do not prvent a residue of liquid from remaining on the end face of the vessel mouth, and in many cases this can lead to soiling or sticking of the vessel closure and is therefore undeseirable. As a result of the use of pouring rings, an additional gap, in which a residue of liquid can collect, is even formed between the pouring ring and the vessel mouth.
It is known that it is possible to do without these advantageous pouring rings if the vessel mouths are provided with a silane coating. The silane coating can be applied, for example, by immersion, by being brushed on or sprayed (U.S. Pat. No. 3,423,234). The silane coating prevents residues of liquid from dripping or from running down and also ensures that the likewise coated endn face of the vessel mouth remains free of liquid residues.
However, the silane coating of vessel mouths has hitherto not been put to practical use, because it has not been possible to carry out the coating operation n an economically satisfactory way during the mass production of glass bottles and other vessels.